Is_prime function via regex in python (from perl)

Question

I've read this article where the /^1?$|^(11+?)\1+$/ Perl regex is used to test if a number is prime or not.

Process:

s = '1' * your_number

If s matchs the regex, then it's not prime. If it doesn't, it's prime.

How would you translate that regex to Python's re module?

Answer 1

It works as is (except without the slashes at the edges, which aren't needed in Python):

pattern = r'^1?$|^(11+?)\1+$'
re.match(pattern, '1'*10)    #matches
re.match(pattern, '1'*11)    #doesn't match

The only nonstandard regex feature needed here is backreferences (\1), and these are supported in both Perl and Python.